The invention generally relates to oil-flooded fluid compressors, and more particularly to an apparatus and method for continuously disposing of liquid condensate in an oil-flooded fluid compressor driven by a prime mover having an exhaust system, and wherein liquid mixed with the compressed fluid is separated from the compressed fluid by at least one liquid separating means, the at least one liquid separating means is continuously purged by compressed system pressure and as a result, the liquid condensate is continuously flowed to the exhaust system, is vaporized by the hot exhaust fluid, and is entrained in the discharged exhaust fluid stream.
During operation of a conventional oil-flooded fluid compressor, oil is injected into the compressor's compression module to reduce the temperature of the hot, compressed fluid, which is typically air. The injected oil and other liquids that are entrained with the compressed fluid must be separated from the compressed fluid before the compressed fluid is supplied to an object of interest such as a pneumatic tool.
Typical fluid compressor systems include an oil-flooded compressor, an aftercooler and an afterfiltration or separation device. The aftercooler and afterfiltration devices are most typically used to respectively reduce the temperature of the compressed fluid, and to separate the liquids from the compressed fluid. The liquid collected during the aftercooling and afterfiltering is flowed from the compressed fluid system to a drum or other suitable holding vessel and is collected in the vessel. The liquid collected in the vessel must then be disposed of from time to time. The collected liquid is frequently considered a hazardous material, which may only be disposed of after either complying with a required disposal procedure or chemically treating the liquid in some manner. As a result, disposal of the separated liquid using such a traditional collection and disposal method is typically quite burdensome and expensive.
One prior art fluid compression system described in U.S. Pat. No. 5,287,916 attempts to overcome the shortcomings associated with traditional collection and disposal methods. Generally, in the '916 patent, the separated liquid is collected in a holding vessel, and periodically, upon reaching a predetermined liquid collection level, is injected by compression system pressure into the exhaust system of a compressor prime mover which causes the liquid to be converted to vapor and entrained in the prime mover exhaust fluid.
Although this system effectively overcomes the shortcomings of the traditional collection and disposal methods, this collection and disposal method also has associated shortcomings. When the system is operated in below freezing ambient temperatures the liquid in the holding vessel can freeze and as a result, each holding vessel must include a heater at an additional cost, to prevent liquid freezing which may damage the holding vessel. In addition to this shortcoming, the apparatus for collecting and injecting the separated liquid from the holding vessel to the exhaust system can be expensive and the mechanism can be unreliable. When the injection apparatus is not functioning properly, the compressed fluid delivered to an object of interest will include an undesirable volume of liquid. A third shortcoming of the system disclosed in the '916 patent is that if there are two or more holding vessels associated with the aftercooler/after filtration devices, each with a condensate drain, each at slightly different pressures due to compressed fluid system component pressure drop, in order for the holding vessels to function properly, it is necessary for the system to include either a separate collection/injection device for each condensate drain, or a series of check valves and timed solenoids to sequentially purge each holding vessel. Such an arrangement significantly increases the system cost, complexity and reliability. Associated with this third shortcoming is the inability of the prior system to be purged automatically. Upon shutdown of the system, the collection/injection devices(s) must be purged of any remaining liquid, either manually or with a solenoid type device, to prevent damage in freezing environments. If the compressor operator forgets to purge the collection system and flow lines, the liquid can freeze in the device(s) and cause significant damage.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide a condensate disposal system to dispose of the liquid condensate which is continuous, automatic, reliable, and minimizes the possibility of condensate disposal system failure during cold (below freezing) operation. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.